core/rawcon.c

   1 /*
   2  * writechr:    Write a single character in AL to the console without
   3  *              mangling any registers.  This does raw console writes,
   4  *              since some PXE BIOSes seem to interfere regular console I/O.
   5  */
   6 #include <sys/io.h>
   7 #include <fs.h>
   8 #include <com32.h>
   9
  10 #include "bios.h"
  11 #include "graphics.h"
  12 #include <syslinux/video.h>
  13
  14 __export void writechr(char data)
  15 {
  16         if (UsingVGA & 0x08)
  17                 syslinux_force_text_mode();
  18
  19         write_serial(data);     /* write to serial port if needed */
  20
  21         /* Write to screen? */
  22         if (DisplayCon & 0x01) {
  23                 com32sys_t ireg, oreg;
  24                 bool curxyok = false;
  25                 uint16_t dx;
  26
  27                 memset(&ireg, 0, sizeof ireg);
  28                 ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  29                 ireg.eax.b[1] = 0x03; /* Read cursor position */
  30                 __intcall(0x10, &ireg, &oreg);
  31                 ireg.edx.l = oreg.edx.l;
  32
  33                 switch (data) {
  34                 case 8:
  35                         if (ireg.edx.b[0]--) {
  36                                 curxyok = true;
  37                                 break;
  38                         }
  39
  40                         ireg.edx.b[0] = VidCols;
  41                         if (ireg.edx.b[1]--) {
  42                                 curxyok = true;
  43                                 break;
  44                         }
  45
  46                         ireg.edx.b[1] = 0;
  47                         curxyok = true;
  48                         break;
  49                 case 13:
  50                         ireg.edx.b[0] = 0;
  51                         curxyok = true;
  52                         break;
  53                 case 10:
  54                         break;
  55                 default:
  56                         dx = ireg.edx.w[0];
  57
  58                         ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  59                         ireg.ebx.b[0] = 0x07; /* White on black */
  60                         ireg.ecx.w[0] = 1;    /* One only */
  61                         ireg.eax.b[0] = data;
  62                         ireg.eax.b[1] = 0x09; /* Write char and attribute */
  63                         __intcall(0x10, &ireg, NULL);
  64
  65                         ireg.edx.w[0] = dx;
  66                         if (++ireg.edx.b[0] <= VidCols)
  67                                 curxyok = true;
  68                         else
  69                                 ireg.edx.b[0] = 0;
  70                 }
  71
  72                 if (!curxyok && ++ireg.edx.b[1] > VidRows) {
  73                         /* Scroll */
  74                         ireg.edx.b[1]--;
  75                         ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  76                         ireg.eax.b[1] = 0x02;
  77                         __intcall(0x10, &ireg, NULL);
  78
  79                         ireg.eax.w[0] = 0x0601; /* Scroll up one line */
  80                         ireg.ebx.b[1] = ScrollAttribute;
  81                         ireg.ecx.w[0] = 0;
  82                         ireg.edx.w[0] = ScreenSize; /* The whole screen */
  83                         __intcall(0x10, &ireg, NULL);
  84                 } else {
  85                         ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  86                         ireg.eax.b[1] = 0x02; /* Set cursor position */
  87                         __intcall(0x10, &ireg, NULL);
  88                 }
  89         }
  90 }
  91
  92 void pm_writechr(com32sys_t *regs)
  93 {
  94         writechr(regs->eax.b[0]);
  95 }